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Abstract:

A method is provided to remove an unexpected pop-up noise that occurs
while audio data such as a key tone is output in an electronic device.
The method includes detecting an interruption such as a key release for
stopping the output of audio data, and verifying Pulse Code Modulation
(PCM) data of the audio data. If there is a gap between an endpoint of
the PCM data and a given reference value, the device reduces the gap by
revising the endpoint of the PCM data.

Claims:

1. A method for removing pop-up noise in an electronic device, the method
comprising:detecting an interruption for stopping the output of audio
data;verifying Pulse Coding Modulation (PCM) data of the audio data;
andwhen there is a gap between an endpoint of the PCM data and a given
reference value, reducing the gap by revising the endpoint of the PCM
data.

2. The method of claim 1, wherein the detecting of the interruption
comprises detecting at least one of a key release and a power-off.

3. The method of claim 1, wherein the verifying of the PCM data includes
analyzing a sine curve obtained from the PCM data and determining whether
an endpoint of the sine curve converges on the reference value at the
time of the interrupt.

4. The method of claim 3, wherein, if the endpoint of the sine curve
converges on the given reference value at the time of at least one of a
key release and a power-off, the output of the audio data is stopped.

5. The method of claim 3, wherein the revising of the endpoint includes
converging the endpoint on the reference value at least one of before and
after the time of the interrupt.

6. The method of claim 5, wherein the output of the audio data is stopped
at the time of at least one of a key release and a power-off when the
revised endpoint of the since curve converges on the reference value.

7. The method of claim 5, wherein the reducing of the gap includes, if the
endpoint fails to converge on the reference value, adding data to the PCM
data so that the endpoint converges on the reference value.

8. The method of claim 5, wherein the reducing of the gap includes, if the
endpoint fails to converge on the reference value, erasing data after the
last point among points of the PCM data converging on the reference value
so that the endpoint converges on the reference value.

9. The method of claim 5, wherein the reducing of the gap
comprises:analyzing an end slope of the sine curve at the time of the
interruption if the endpoint of the PCM data fails to converge on the
reference value;if the end slope has an inward direction to the reference
value, extending the sine curve to the reference value so that the
endpoint converges on the reference value; andif the end slope has an
outward direction from the reference value, erasing the sine curve after
the last point among points of the sine curve converging on the reference
value so that the endpoint converges on the reference value.

10. A method for removing pop-up noise in an electronic device, the method
comprising:outputting a key tone in response to a received key
input;analyzing a sine curve of the key tone when detecting a key release
during the output of the key tone;stopping the output of the key tone at
the time of the key release if an endpoint of the sine curve converges on
a given reference value;revising the key tone if the endpoint of the sine
curve fails to converge on the reference value; andstopping the output of
the key tone at the time when the endpoint of the sine curve of the
revised key tone converges on the reference value.

11. The method of claim 10, wherein the analyzing of the sine curve
includes determining whether the endpoint of the sine curve converges on
the reference value at the time of the key release.

12. The method of claim 11, wherein the analyzing of the sine curve
includes determining whether there is a gap between the endpoint of the
sine curve and the reference value.

13. The method of claim 12, wherein the revising of the key tone includes
converging the endpoint on the reference value at least one of before and
after the time of the key release.

14. The method of claim 13, wherein the revising of the key tone includes
extending the sine curve so that the endpoint converges on the reference
value.

15. The method of claim 13, wherein the revising of the key tone includes
erasing a portion of the sine curve after the last point among points of
the sine curve converging on the reference value so that the endpoint
converges on the reference value.

16. The method of claim 13, wherein the revising of the key tone
comprises:analyzing an end slope of the sine curve at the time of the key
release if the endpoint of the since curve fails to converge on the
reference value;if the end slope has an inward direction to the reference
value, extending the sine curve to the reference value so that the
endpoint converges on the reference value; andif the end slope has an
outward direction from the reference value, erasing the sine curve after
the last point among points of the sine curve converging on the reference
value so that the endpoint converges on the reference value.

17. The method of claim 10, wherein the pop-up noise occurs when the key
release occurs before a preset output duration of the key tone.

Description:

PRIORITY

[0001]This application claims the benefit under 35 U.S.C. §119(a) of
a Korean patent application filed on Sep. 2, 2009 in the Korean
Intellectual Property Office and assigned Serial No. 10-2009-0082593, the
entire disclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002]1. Field of the Invention

[0003]The present invention relates to a mobile device. More particularly,
the present invention relates to a method for removing pop-up noise
resulting from an output stop in audio data in a mobile device.

[0004]2. Description of the Related Art

[0005]In mobile devices, an unexpected pop-up noise may sometimes occur
while audio data such as a key tone is output. The pop-up noise is a
large pulse that is produced at a time when the output of audio data is
suddenly stopped due to an interruption.

[0006]All electronic devices such as a mobile device that are capable of
outputting audio data may unexpectedly encounter pop-up noise. Naturally,
the pop-up noise may depend on the time when the output of audio data is
stopped. In addition, the pop-up noise may only occur by means of Pulse
Coding Modulation (PCM) of data without any changes to an audio path and
without interference by hardware noises.

[0007]The pop-up noise that occurs during audio data output in the mobile
device may result in user discomfort and inconvenience.

[0008]Therefore, a need exists for a method for removing pop-up noise in a
mobile device.

SUMMARY OF THE INVENTION

[0009]An aspect of the present invention is to address at least the
above-mentioned problems and/or disadvantages and to provide at least the
advantages described below. Accordingly, an aspect of the present
invention is to provide a method for removing pop-up noise in a mobile
device.

[0010]Another aspect of the present invention is to provide a method for
removing pop-up noise occurring when audio data output is stopped due to
interruption in a mobile device.

[0011]Still another aspect of the present invention is to provide a method
for removing pop-up noise in connection with a key tone output in a
mobile device.

[0012]Yet another aspect of the present invention is to provide a method
for removing pop-up noise occurring when a key tone output is stopped
prior to the expiration of a preset output duration due to interruption
in a mobile device.

[0013]Further an aspect of the present invention is to provide a method
for removing pop-up noise by revising an endpoint of a key tone to
converge on a given reference value when a key tone output is stopped due
to interruption.

[0014]Still a further aspect of the present invention is to provide a
method for removing pop-up noise by delaying the output stop time of a
key tone until the time when an endpoint of a key tone converges on a
given reference value rather than the time when interruption occurs, if
an endpoint of a key tone fails to converge on the given reference value
at that interruption time.

[0015]In accordance with an aspect of the present invention, a method for
removing pop-up noise in an electronic device is provided. The method
includes detecting an interruption for stopping the output of audio data,
verifying Pulse Coding Modulation (PCM) data of the audio data, and, when
there is a gap between an endpoint of the PCM data and a given reference
value, reducing the gap by revising the endpoint of the PCM data.

[0016]The verifying of the PCM data may include analyzing a sine curve
obtained from the PCM data and determining whether the endpoint of the
sine curve converges on the reference value at the time of the
interruption.

[0017]The revising of the endpoint may include converging the endpoint on
the reference value before or after the time of the interrupt.

[0018]If the endpoint fails to converge on the reference value, the
reducing of the gap may include adding data to the PCM data so that the
endpoint converges on the reference value.

[0019]If the endpoint fails to converge on the reference value, the
reducing of the gap may include erasing data after the last point among
points of the PCM data converging on the reference value so that the
endpoint converges on the reference value.

[0020]The reducing of the gap may include analyzing an end slope of the
sine curve at the time of the interruption if the endpoint of the PCM
data fails to converge on the reference value, if the end slope has an
inward direction to the reference value, extending the sine curve to the
reference value so that the endpoint converges on the reference value,
and if the end slope has an outward direction from the reference value,
erasing the sine curve after the last point among points of the sine
curve converging on the reference value so that the endpoint converges on
the reference value.

[0021]The pop-up noise may occur when the interruption occurs before a
preset output duration of the audio data ends.

[0022]In accordance with another aspect of the present invention, a method
for removing pop-up noise in an electronic device is provided. The method
includes outputting a key tone in response to a received key input,
analyzing a sine curve of the key tone when detecting a key release
during the output of the key tone, stopping the output of the key tone at
the time of the key release if an endpoint of the sine curve converges on
a given reference value, revising the key tone if the endpoint of the
sine curve fails to converge on the reference value, and stopping the
output of the key tone at the time when the endpoint of the sine curve of
the revised key tone converges on the reference value.

[0023]In accordance with still another aspect of the present invention, a
method for removing pop-up noise in an electronic device is provided. The
method includes detecting an interruption for stopping the output of
audio data, analyzing a sine curve of the audio data, when there is a gap
between an endpoint of the sine curve and a given reference value,
revising the sine curve, and stopping the output of the audio data at the
endpoint of the revised sine curve.

[0024]Other aspects, advantages, and salient features of the invention
will become apparent to those skilled in the art from the following
detailed description, which, taken in conjunction with the annexed
drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]The above and other aspects, features, and advantages of certain
exemplary embodiments of the present invention will be more apparent from
the following description taken in conjunction with the accompanying
drawings, in which:

[0026]FIG. 1 illustrates a key tone output in response to a key press that
is longer than a preset output duration of the key tone in a mobile
device according to an exemplary embodiment of the present invention.

[0027]FIGS. 2A and 2B illustrate a key tone output in response to a key
press that is shorter than a preset output during a key tone in a mobile
device and an example of pop-up noise according to an exemplary
embodiment of the present invention.

[0028]FIGS. 3A and 3B illustrate a method for removing pop-up noise
occurring when a key tone output is stopped according to an exemplary
embodiment of the present invention.

[0029]FIGS. 4A and 4B illustrate a method for removing pop-up noise
occurring when a key tone output is stopped according to an exemplary
embodiment of the present invention.

[0030]FIGS. 5A and 5B illustrate a method for removing pop-up noise
occurring when a key tone output is stopped according to an exemplary
embodiment of the present invention.

[0031]FIG. 6 is a flow diagram illustrating a method for removing pop-up
noise in a mobile device according to an exemplary embodiment of the
present invention.

[0032]FIG. 7 is a flow diagram illustrating a method for removing pop-up
noise in a mobile device according to an exemplary embodiment of the
present invention.

[0033]Throughout the drawings, it should be noted that like reference
numbers are used to depict the same or similar elements, features, and
structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0034]The following description with reference to the accompanying
drawings is provided to assist in a comprehensive understanding of
exemplary embodiments of the invention as defined by the claims and their
equivalents. It includes various specific details to assist in that
understanding but these are to be regarded as merely exemplary.
Accordingly, those of ordinary skill in the art will recognize that
various changes and modifications of the embodiments described herein can
be made without departing from the spirit and scope of the invention.
Also, descriptions of well-known functions and constructions are omitted
for clarity and conciseness.

[0035]The terms and words used in the following description and claims are
not limited to the bibliographical meanings, but, are merely used by the
inventor to enable a clear and consistent understanding of the invention.
Accordingly, it should be apparent to those skilled in the art that the
following description of exemplary embodiments of the present invention
are provided for illustration purpose only and not for the purpose of
limiting the invention as defined by the appended claims and their
equivalents.

[0036]It is to be understood that the singular forms "a," "an," and "the"
include plural referents unless the context clearly dictates otherwise.
Thus, for example, reference to "a component surface" includes reference
to one or more of such surfaces.

[0037]Exemplary embodiments of the present invention provide a method for
removing pop-up noise resulting from a stop in audio data output in a
mobile device. More particularly, exemplary embodiments of the present
invention provide a method for removing pop-up noise through
software-based processing regardless of any change of audio paths or
interference by hardware such as a speaker. Furthermore, exemplary
embodiments of the present invention provide a method for removing pop-up
noise in electronic devices including, but not limited to, a mobile
device when the audio data output is suddenly stopped.

[0038]Normally, in an electronic device capable of outputting audio data,
the output of audio data such as a key tone may be suddenly stopped. At
this time, an unexpected pop-up noise may occur due to Pulse Coding
Modulation (PCM) of data without any change of an audio path and without
interference by hardware noises, based on the output stop time of the
audio data. The pop-up noise will be described in more detail below with
reference to FIGS. 1, 2A and 2B.

[0039]FIG. 1 illustrates a key tone output in response to a key press that
is longer than a preset output duration of a key tone in a mobile device
according to an exemplary embodiment of the present invention. FIGS. 2A
and 2B illustrate a key tone output in response to a key press that is
shorter than a preset output during a key tone in a mobile device and an
example of pop-up noise according to an exemplary embodiment of the
present invention.

[0040]FIGS. 1, 2A and 2B illustrate a sine curve of a key tone as an
example of audio data. Typically, a key tone is output when each
alphanumeric key is pressed in any operation mode (e.g., a dialing mode)
of a mobile device.

[0041]FIG. 1 illustrates a case where a certain key is pressed longer than
a preset output duration of a key tone assigned to a pressed key
according to an exemplary embodiment of the present invention.

[0042]Referring to FIG. 1, reference number 110 denotes a key press start
time, i.e., the time when a user's key press occurs, and reference number
130 denotes a key release time, i.e., the time when the user's key press
is released. Additionally, reference number 150 denotes a sine curve of a
key tone assigned to a pressed key, and reference number 170 denotes a
preset output duration of the key tone.

[0043]As illustrated in FIG. 1, the key tone output begins at the key
press start time 110 and continues within a preset output duration while
the key press is maintained without releasing the key press. This is a
normal case in which an entire key tone is completely output since the
key press is longer than the preset output duration of the key tone. That
is, as denoted by reference number 130, the key release occurs after the
output of the key tone is complete. In this case, pop-up noise may not
occur.

[0044]On the contrary, FIGS. 2A and 2B illustrate a case where a certain
key is pressed shorter than a preset output duration of a key tone
assigned to a pressed key.

[0045]Referring to FIGS. 2A and 2B, reference number 210 denotes a key
press start time, and reference number 230 denotes a key release time.
Additionally, reference number 250 denotes a sine curve of a key tone
originally assigned to a pressed key in a case where a key tone is output
until the preset output duration expires. Meanwhile, reference number 270
denotes a sine curve of the key tone in a case where the output of the
key tone is stopped by the key release before the preset output duration
expires.

[0046]As illustrated in FIGS. 2A and 2B, the key tone output starts at the
key press start time 210. The output of the key tone continues during the
key press and stops at the key release time. More specifically, FIGS. 2A
and 2B illustrate a case in which an entire key tone is not completely
output since the key press is shorter than the preset output duration of
the key tone. In this case, pop-up noise may occur, based on a wave form
of the sine curve at the key release time. FIG. 2A illustrates a case in
which the pop-up noise occurs, and FIG. 2B illustrates a case in which
the pop-up noise does not occur.

[0047]Referring to FIG. 2A, at the time of the key release, the sine curve
of the key tone stops at a distance far from the reference value. In this
case, the pop-up noise may occur when the output of the key tone is
stopped. For example, if an endpoint of the sine curve is separated from
the reference value when the output of the key tone is suddenly stopped
due to the key release, the pop-up noise is created instantaneously in
the form of a large pulse.

[0048]Referring to FIG. 2B, at the time of the key release, the sine curve
of the key tone stops at a distance close to the reference value. In this
case, the pop-up noise may not occur when the output of the key tone is
stopped. For example, if an endpoint of the sine curve is very close to
the reference value when the key tone output is suddenly stopped due to
the key release, the pop-up noise is not created and the output of the
key tone is normally stopped.

[0049]As described above, audio data (e.g., a key tone) output in response
to a user's key press may cause an unexpected pop-up noise, based on a
relationship between the key release time and a preset output duration of
the audio data. More specifically, if the audio data output is stopped
due to the key release before the original output duration expires, the
pop-up noise may occur according to the wave form of the sine curve at
the key release time. That is, if the endpoint of the sine curve is
separated from the reference value (e.g., zero) at the key release time,
the pop-up noise is created.

[0050]Therefore, the pop-up noise that may occur when the audio data
output is stopped compulsorily due to the key release prior to the
expiration of the preset output duration may be removed according to an
exemplary embodiment of the present invention. In an exemplary
implementation, the pop-up noise may be removed by analyzing the sine
curve at the key release time and then revising the endpoint of the sine
curve to converge on the reference value. In this case, a revision for
the endpoint of the sine curve may be varied based on whether an end
slope of the sine curve approaches the reference value.

[0051]Exemplary methods for revising the audio data will be described in
more detail below. The following examples are exemplary only and should
not limit the scope of the invention.

[0052]FIGS. 3A and 3B illustrate a method for removing pop-up noise
occurring when a key tone output is stopped according to an exemplary
embodiment of the present invention.

[0053]Audio data as illustrated in FIGS. 3A and 3B may be revised by
making an endpoint of a sine curve converge on a reference value.

[0054]Referring to FIGS. 3A and 3B, reference number 310 denotes a preset
sine curve of a key tone originally assigned to a pressed key, i.e., in a
case where a key tone is output until a preset output duration expires.
Reference number 330 denotes the key release time, and reference number
350 denotes an actual sine curve of the key tone in a case where pop-up
noise occurs, i.e., in which an endpoint of the sine curve is separated
from the reference value when the key tone output is stopped in response
to a key release. Additionally, reference number 370 denotes a revised
sine curve of the key tone in which the sine curve is extended to
converge on the reference value, and reference number 390 denotes a new
endpoint of the sine curve after being revised.

[0055]Referring to FIGS. 3A and 3B, the revision method to remove the
pop-up noise extends the sine curve of the key tone so that an endpoint
390 of the sine curve may approach the reference value. More
particularly, FIGS. 3A and 3B illustrate examples adopting a method for
reducing a gap between the endpoint 390 of the sine curve and the
reference value by extending the sine curve where the endpoint of the
actual sine curve 350 is separated from the reference value.

[0056]More specifically, FIG. 3A illustrates an example of the key tone
output in which an actual sine curve 350 has an inward end slope, i.e.,
an end slope that runs toward the reference value. In this case, as
denoted by reference number 370, the sine curve of the key tone is
revised, i.e., extended, so that the endpoint 390 of the sine curve may
converge on the reference value. Additionally, the key tone output is
stopped at the revised end point 390 on the reference value rather than
at the key release time 330. The key tone output is stopped in response
to a virtual key release instead of an actual key release. Therefore, the
gap between the endpoint 390 of the sine curve and the reference value is
reduced. Thereby, an unexpected pop-up noise is removed.

[0057]On the other hand, FIG. 3B illustrates an example of the key tone
output in which the actual sine curve 350 has an outward end slope. In
this case, as well as in the above case, as denoted by reference number
370, the sine curve of the key tone is revised, i.e., extended, so that
the endpoint 390 of the sine curve may converge on the reference value.
Additionally, the key tone output is stopped at the revised end point 390
on the reference value rather than the key release time 330. That is, the
key tone output is stopped in response to the virtual key release instead
of the actual key release. Therefore, the gap between the endpoint 390 of
the sine curve and the reference value is reduced. Thereby, the
unexpected pop-up noise is removed.

[0058]FIGS. 4A and 4B illustrate a method for removing pop-up noise
occurring when a key tone output is stopped according to an exemplary
embodiment of the present invention.

[0059]More particularly, a revision method illustrated in FIGS. 4A and 4B
uses a last point just before a key release among points of a sine curve
converging on a reference value.

[0060]Referring to FIGS. 4A and 4B, reference number 410 denotes a preset
sine curve of a key tone originally assigned to a pressed key, i.e., in a
case where a key tone is output until a preset output duration expires.
Reference number 430 denotes the key release time, and reference number
450 denotes an actual sine curve of the key tone in a case where pop-up
noise occurs, i.e., in which an endpoint of the sine curve is separated
from the reference value when the key tone output is stopped in response
to the key release. Additionally, reference number 490 denotes the last
point just before an actual key release 430 among points of the sine
curve converging on the reference value, reference number 435 denotes a
virtual key release corresponding to the last point 490, and reference
number 470 denotes a revised sine curve of a key tone in which a portion
after the virtual key release 435 is erased and hence the endpoint
converges on the reference value.

[0061]In FIGS. 4A and 4B, in the revision method to remove the pop-up
noise, the last point 490 before the actual key release 430 among points
of the sine curve converging on the reference value is selected and then
a portion of the sine curve after the last point 490 is erased.
Consequently, the revised sine curve 470 has an endpoint converging on
the reference value. More specifically, FIGS. 4A and 4B illustrate
examples adopting a method for reducing a gap between the endpoint of the
sine curve and the reference value by erasing the sine curve after the
last point 490 converging on the reference value, in a case where the
endpoint of the actual sine curve 450 is separated from the reference
value.

[0062]More specifically, FIG. 4A illustrates an example of the key tone
output in which the actual sine curve 450 has an inward end slope, i.e.,
an end slope that runs toward the reference value. In this case, as
denoted by reference number 470, the sine curve of the key tone after the
last point 490 converging on the reference value is erased and the output
of the key tone is stopped at the last converging point 490 rather than
at the key release time 430. The output of the key tone is stopped in
response to the virtual key release 435 produced at the last converging
point 490 instead of in response to the actual key release 430.
Therefore, the gap between the endpoint of the sine curve and the
reference value is reduced. Thereby, an unexpected pop-up noise is
removed.

[0063]On the other hand, FIG. 4B illustrates an example of the key tone
output in which the actual sine curve 450 has an outward end slope. In
this case as well as in the above case, as denoted by reference number
470, the sine curve of the key tone after the last point 490 converging
on the reference value is erased and the output of the key tone is
stopped at the last converging point 490 rather than at the key release
time 430. That is, the output of the key tone is stopped in response to
the virtual key release 435 produced at the last converging point 490
instead of at the actual key release 430. Therefore, the gap between the
endpoint of the sine curve and the reference value is reduced. Thereby,
the unexpected pop-up noise is removed.

[0064]As described above, exemplary embodiments of the present invention
illustrated in FIGS. 3A to 4B provide a method for removing pop-up noise
that may occur when the audio data output is stopped compulsorily due to
the key release interruption prior to the expiration of the preset output
duration. More particularly, for removing the pop-up noise, FIGS. 3A and
3B adopt a revision method for adding data, and FIGS. 4A and 4B adopt a
revision method for erasing data.

[0065]Meanwhile, with reference to FIGS. 5A and 5B, the methods between
both revisions may be adopted. That is, the following methods to remove
pop-up noise as illustrated in FIGS. 5A and 5B may be selectively used
based on the type of end slope of a sine curve.

[0066]FIGS. 5A and 5B illustrate a method for removing pop-up noise
occurring when a key tone output is stopped according to an exemplary
embodiment of the present invention.

[0067]More particularly, a revision method illustrated in FIGS. 5A and 5B
analyzes a sine curve around an interruption time and then adds data or
erases data based on whether an end slope of a sine curve approaches a
reference value.

[0068]Referring to FIGS. 5A and 5B, reference number 510 denotes a preset
sine curve of a key tone originally assigned to a pressed key, i.e., in a
case where a key tone is output until a preset output duration expires.
Reference number 530 denotes the key release time, and reference number
550 denotes an actual sine curve of a key tone in a case where pop-up
noise occurs, i.e., in which an endpoint of a sine curve is separated
from a reference value when the output of the key tone is stopped in
response to a key release. Additionally, reference number 570 denotes a
revised sine curve of the key tone in which the sine curve is extended to
converge on the reference value, and reference number 575 denotes a new
endpoint of the sine curve after being revised. Furthermore, reference
number 595 denotes the last point just before an actual key release 530
among points of a sine curve converging on a reference value, reference
number 535 denotes a virtual key release corresponding to the last point
595, and reference number 590 denotes a revised sine curve of the key
tone in which a portion after the virtual key release 535 is erased and
hence the endpoint converges on the reference value.

[0069]Referring to FIGS. 5A and 5B, the revision method to remove pop-up
noise either extends the sine curve of the key tone in order for the
endpoint to approach the reference value (illustrated in FIG. 5A) or
erases a portion of the sine curve after the last point before the actual
key release 530 among points of the sine curve converging on the
reference value (illustrated in FIG. 5B), based on whether the end slope
of the sine curve approaches a reference value. More particularly, FIGS.
5A and 5B illustrate a combined method of the methods illustrated in
FIGS. 3A to 4B.

[0070]More specifically, as described above in FIG. 3A, FIG. 5A
illustrates an example of a key tone output in which the actual sine
curve 550 has an inward end slope, i.e., an end slope that runs toward
the reference value. In this case, as denoted by reference number 570,
the sine curve of the key tone is revised, i.e., extended, so that the
endpoint 575 of the sine curve may converge on the reference value.
Additionally, the output of the key tone is stopped at the revised end
point 575 on the reference value rather than at the key release time 530.
More particularly, the key tone output is stopped in response to the
virtual key release instead of in response to the actual key release.
Therefore, a gap between the endpoint of the sine curve and the reference
value is reduced. Thereby, an unexpected pop-up noise is removed.

[0071]On the other hand, as described above in FIG. 4B, FIG. 5B
illustrates an example of a key tone output in which the actual sine
curve 550 has an outward end slope. In this case as well as in the above
case, as denoted by reference number 590, the sine curve of the key tone
after the last point 595 converging on the reference value is erased and
the output of the key tone is stopped at the last converging point 595
rather than at the key release time 530. That is, the output of the key
tone is stopped in response to the virtual key release 535 produced at
the last converging point 595 instead of at the actual key release.
Therefore, the gap between the endpoint of the sine curve and the
reference value is reduced. Thereby, the unexpected pop-up noise is
removed.

[0072]In summary, exemplary embodiments of the present invention
illustrated in FIGS. 5A and 5B analyze the end slope of the sine curve if
the end point of the sine curve fails to converge on the reference value.
Then, the sine curve is erased after the last converging point if the end
slope has an outward direction, i.e., becomes more distant from the
reference value, or the sine curve is extended to the reference value if
the end slope has an inward direction, i.e., approaches the reference
value. By increasing or decreasing the sine curve according to the type
of end slope, a gap between the endpoint of the sine curve and the
reference value may be reduced.

[0073]As described above, in an electronic device capable of outputting
audio data, if the output of the audio data such as a key tone is
suddenly stopped due to interruption and the endpoint of its sine curve
is separated from the reference value, pop-up noise may occur. As
described in FIGS. 3A to 5B, the aforesaid pop-up noise is substantially
removed by converging the endpoint of the sine curve on the reference
value and hence reducing the gap between the endpoint and the reference
value.

[0074]A method for removing pop-up noise in a mobile device will be
described below according to an exemplary embodiment of the present
invention. The following method is exemplary only and should not limit
the scope of the invention.

[0075]FIG. 6 is a flow diagram illustrating a method for removing pop-up
noise in a mobile device according to an exemplary embodiment of the
present invention.

[0076]Referring to FIG. 6, at the outset, the mobile device outputs audio
data at a user's request in step 601. Here, a user's request may be a
user's pressing action on a selected key. Therefore, the output of the
audio data may be the output of a key tone assigned to a pressed key.

[0077]The mobile device determines whether there is an interruption for
stopping the output of the audio data in step 603. Here, the interruption
may be a user's releasing action from the pressed key. That is, a user
may release the key after a certain time from a key press.

[0078]The mobile device analyzes a sine curve of the audio data at the
time of the key release in step 605. The mobile device may analyze the
endpoint of the sine curve and its end slope at the key release time. In
addition, the mobile device determines whether the endpoint converges on
a given reference value such as zero in step 607.

[0079]If it is determined that the endpoint converges on the given
reference value in step 607, the mobile device stops the output of the
audio data without any revision of the audio data in step 609.

[0080]On the contrary, if it is determined that the endpoint fails to
converge on the given reference value in step 607, the mobile device
performs a preset revision of the audio data in step 611. More
specifically, the mobile device revises the sine curve of the audio data.
Here, as discussed above in FIGS. 3A to 5B, the revision is to either
extend or erase the sine curve of the audio data so that the endpoint of
the sine curve may converge on the reference value.

[0081]At the time when the endpoint of the sine curve converges on the
reference value by the revision method such as addition or erasure of
data, the mobile device stops the output of the audio data in step 613.
Here, the mobile device may create a virtual key release at the time when
the endpoint of the sine curve converges on the reference, and then may
stop the output of the audio data such as the key tone in response to the
virtual key release.

[0082]FIG. 7 is a flow diagram illustrating a method for removing pop-up
noise in a mobile device according to an exemplary embodiment of the
present invention.

[0083]Referring to FIG. 7, at the outset, the mobile device receives a key
input from a user in step 701. The mobile device then outputs a preset
key tone assigned to a selected key in response to the above user's key
input in step 703. Thereafter, the mobile device determines whether a key
is released from the above selected key in step 705.

[0084]The mobile device determines whether a key input span is equal to or
greater than a given threshold value (Th) at the time of the key release
in step 707. More specifically, the mobile device determines whether the
length of time from a key input to a key release is equal to or greater
than a given threshold value (Th). Accordingly, the mobile device may
verify whether a certain key is pressed longer or shorter than a preset
output duration of a key tone. Thus, in step 707, whether the key tone is
output until a preset output duration expires may be determined.

[0085]If it is determined that the key input span is equal to or greater
than a threshold value (Th) in step 707, the mobile device normally stops
the output of a key tone in step 713. That is, if it is determined that
the selected key is pressed longer than the preset output duration of the
key tone, the mobile device closes the output of a key tone according to
the preset output duration of the key tone.

[0086]On the contrary, if is determined that the key input span is smaller
than the threshold value (Th) in step 707, the mobile device analyzes the
sine curve of the key tone in step 709. That is, if the selected key is
pressed shorter than the preset output duration of the key tone, the
mobile device analyzes the endpoint of the sine curve and its end slope.

[0087]In step 709, the analysis of the sine curve may include receiving
the key tone from a memory, performing a Pulse Coding Modulation (PCM)
process for the received key tone, and then analyzing resultant PCM data.
More particularly, the analysis may verify whether the endpoint of PCM
data is separated from the reference value. Normally, PCM is a digital
representation of an analog signal in which the magnitude of the signal
is sampled regularly at uniform intervals. This is often referred to as a
sampling of signals based on time division. The magnitude of the sampled
signal has simple values through quantization. Quantized magnitude values
are expressed by means of a binary notation and then converted into
pulses, thus producing a pulse signal (i.e., a digital signal) of a
continuously varying signal (i.e., an analog signal).

[0088]Additionally, the mobile device determines whether the endpoint of
the sine curve converges on or is separated from the reference value,
using the above analysis results in step 711.

[0089]If it is determined that the endpoint of a sine curve converges on
the reference value in step 711, the mobile device stops the output of
the key tone in step 713. That is, the mobile device normally stops the
output of the key tone without any revision of the key tone in response
to the key release time.

[0090]On the contrary, if it is determined that the endpoint of the since
curve is separated from the reference value in step 711, the mobile
device performs a preset revision of the key tone in step 715. That is,
the mobile device revises the sine curve of the key tone. Here, as
described above in FIGS. 3A to 5B, the revision is to either extend or
erase the sine curve of the key tone so that the endpoint of the sine
curve may converge on the reference value.

[0091]At the time when the endpoint of the sine curve converges on the
reference value by revision such as addition or erasure of data, the
mobile device stops the output of the key tone in step 717. Here, the
mobile device may create a virtual key release at the time when the
endpoint of the sine curve converges on the reference, and then may close
the output of the key tone in response to the virtual key release.

[0092]As described above, if any interruption occurs to stop the output of
the audio data, the mobile device analyzes the sine curve (i.e., PCM
data) of the audio data at the time of the interruption. Also, if there
is a gap between the endpoint of the sine curve and the reference value,
the mobile device removes pop-up noise by reducing the gap.

[0093]Although exemplary embodiments of the present invention use a key
tone as an example of audio data and a key release as interruption for
stopping a key tone output, the key tone and the key release are
exemplary only and should not limit the scope of the invention.

[0094]Alternatively, any other type of audio data such as MP3 file data
may be used, and any other type of interruption such as power-off may be
used for stopping the output of the audio data. For example, if an
interruption occurs to turn off the power while a selected MP3 file is
playing, the mobile device analyzes a sine curve of the MP3 file data at
the interruption time. The mobile device reduces a difference from a
reference value by performing a revision process as described above
before turning off the power. Therefore, the mobile device can remove
pop-up noise due to the power-off and hence may perform a normal process
related to the power-off.

[0095]As described above, exemplary embodiments of the present invention
provide a method for removing pop-up noise in an electronic device, such
that pop-up noise occurring unexpectedly in audio data such as a key tone
can be easily removed. More particularly, the exemplary embodiments of
the present invention provide a method for removing pop-up noise
occurring when the output of audio data is stopped before a preset output
duration expires. Accordingly, user's discomfort and inconvenience caused
by the sudden output stop of audio data may be eliminated.

[0096]In accordance with the exemplary embodiments of the present
invention, when the output of audio data is stopped due to interruption
occurring before the preset output duration expires, PCM data of the
audio data can be revised and a virtual interruption based on the
revision of PCM data can be provided. In addition, the output of audio
data at the virtual interruption time continues rather than at the actual
interruption time in order to remove the pop-up noise.

[0097]The above-described methods according to the present invention can
be realized in hardware or as software or computer code that can be
stored in a recording medium such as a CD ROM, an RAM, a floppy disk, a
hard disk, or a magneto-optical disk or downloaded over a network, so
that the methods described herein may be rendered in such software using
a general purpose computer, or a special processor or in programmable or
dedicated hardware, such as an Application Specific Integrated Circuit
(ASIC) or Field Programmable Gate Array (FPGA). As would be understood in
the art, the computer, the processor or the programmable hardware include
memory components, e.g., RAM, ROM, Flash, and the like, that may store or
receive software or computer code that when accessed and executed by the
computer, processor or hardware implement the processing methods
described herein. In addition, it would be recognized that when a general
purpose computer accesses code for implementing the processing shown
herein, the execution of the code transforms the general purpose computer
into a special purpose computer for executing the processing shown
herein.

[0098]While the invention has been shown and described with reference to
certain exemplary embodiment thereof, it will be understood by those
skilled in the art that various changes in form and details may be made
therein without departing from the spirit and scope of the invention as
defined by the appended claims and their equivalents.